nrf51822 and oled ssd1306 without softdevicehttps://devzone.nordicsemi.com/f/nordic-q-a/35452/nrf51822-and-oled-ssd1306-without-softdeviceHello SDK12.3, nRF51822 I&#39;m trying to interface the ssd1306 the program freezes in function app_twi_perform internal_transaction_cb is not called internal_transaction_in_progress is not reset. if you use the SoftDevice (instead of lfclk_config callen-USTelligent Community 13Tue, 19 Jun 2018 12:52:45 GMTRE: nrf51822 and oled ssd1306 without softdevicehttps://devzone.nordicsemi.com/thread/136758?ContentTypeID=1Tue, 19 Jun 2018 12:52:45 GMT137ad170-7792-4731-bb38-c0d22fbe4515:a0b8ef2d-e11b-41d5-bf04-6c4523e255f9Susheel Nuguru<p>which clock configuration does your hardware have for HFCLK and LFCLK? Since you said that initialising ble stack fixes problem, it could</p> <ol> <li>selecting wrong clock sources in sdk_config.h&nbsp; (NRFX_CLOCK_CONFIG_LF_SRC)&nbsp; &nbsp; or</li> <li>you might need to start the HFCLK explicitly if you are using XTAL for HFCLK.&nbsp;nrf_drv_clock_hfclk_request</li> </ol><div style="clear:both;"></div>